Some known drainage devices comprise a frame that can be fixed to the channel body. The frame so attached serves to reinforce the upper edge of the channel body and also provides a surface on which the cover is seated. The frame is made of metal and fixed to the channel body.
The German patent DE 40 07 296 C2 discloses a drainage channel in which a frame set onto the upper edge of the channel body is kept in place by external and internal arms of the frame that enclose the wall of the channel body. In addition, the frame is provided with an anchoring projection attached to one of the arms, which when the frame is in the completely installed state engages with an insertion groove that runs within the edge of the channel, so that a bayonet-like connection is produced between the frame and the channel body. However, this drainage channel is very expensive to manufacture, because each frame must be constructed to correspond to the dimensions of the particular channel body.